Control system for controlling a landing gear drive system

ABSTRACT

A control system for controlling a landing gear drive system for driving rotation of an aircraft wheel is disclosed having a control panel with a controller having a forward motion setting and a zero speed setting, a control unit for receiving a control input from the controller, and for providing a torque command to be applied to the wheel, and a speed sensor for sensing an aircraft taxi speed and for providing an indication of the aircraft taxi speed to the control unit. When the controller is moved from the forward motion setting to the zero speed setting, the control unit provides a torque command to the drive system to provide zero forwards driving torque to the wheel, and a braking command to apply a braking torque to the wheel.

CROSS RELATED APPLICATION

This application claims priority to United Kingdom (GB) PatentApplication 1917559.5, filed Dec. 2, 2019, the entire contents of whichare hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present disclosure relates to control systems for controlling alanding gear drive system of an aircraft.

The present invention concerns a control system. More particularly, butnot exclusively, this invention concerns a control system forcontrolling a landing gear drive system on an aircraft, the drive systembeing capable of driving rotation of a wheel of the aircraft, thecontrol system comprising a control panel, provided with a controller, acontrol unit for receiving a control input from the controller, and forproviding a torque command to be applied to the wheel, and a speedsensor for sensing an aircraft taxi speed and for providing anindication of the aircraft taxi speed to the control unit.

The invention also concerns other control systems, an aircraft, methodsof controlling an aircraft landing gear drive system and a controlpanel.

US 2015/0225075 describes a control system for an aircraft landing geardrive system. FIG. 1 is a representation of a controller 10 of such asystem. The controller 10 has three different settings; a backwardsspeed setting 11, a zero setting 12 and a forward speed setting 13. Whenin the forward speed setting 13, the system provides an amount of torqueto the drive system based on the position of a controller within theforward speed setting. In other words, the controller dictates how muchtorque is provided. However, even in a maximum forwards setting 14, thismay not be sufficient to maintain a forwards motion of the aircraft. Forexample if the aircraft is going up hill, a low forwards driving torquelevel may not provide a forwards motion.

In the backwards speed setting 11, the amount of backwards drivingtorque supplied is based on the speed of the aircraft, such that thespeed is maintained to be at or near 2 knots (backwards). When thecontroller is moved from the backwards speed setting to the zero setting12 (arrow 15), the torque supplied is adjusted, and brakes applied, soas to slow the aircraft down to, and then maintain, zero speed. The parkbrake of the aircraft can then be applied.

When the controller is moved from the forwards speed setting 13 to thezero setting 12 (arrow 16), the forwards driving torque supplied isreduced to zero. However, this does not necessarily result in theaircraft slowing down to and maintaining zero speed (for example, if itwas on a slope). Hence, it has been realised that the zero setting hastwo different ways of operating depending on where the controller hasbeen moved from to get to that setting. Hence, a pilot may not be clearon whether or not the aircraft will be slow to and/or hold zero speed inthe zero setting.

It is also difficult to control the speed of the aircraft when movingforwards at a low speed. This makes parking the aircraft (nose in) at anaircraft gate very difficult and may lead to damage if a low speedimpact occurs between an aircraft and an aircraft gate.

In addition, there is no way of ensuring that the aircraft can moveeffectively (i.e. quick enough) up a hill or across a runway, if needed,without providing an oversized drive system.

The present invention seeks to mitigate the above-mentioned problems.Alternatively or additionally, the present invention seeks to provide animproved control system.

SUMMARY OF THE INVENTION

The present invention provides, according to a first aspect, a controlsystem for controlling a landing gear drive system on an aircraft, thedrive system being capable of driving rotation of a wheel of theaircraft, the control system comprising a control panel, provided with acontroller, the controller having at least two settings; a forwardmotion setting, and a zero speed setting, a control unit for receiving acontrol input from the controller, and for providing a torque command tobe applied to the wheel, and a speed sensor for sensing an aircraft taxispeed and for providing an indication of the aircraft taxi speed to thecontrol unit, wherein the control unit is arranged such that, when thecontroller is moved from the forward motion setting to the zero speedsetting, the control unit provides a torque command to the drive systemto provide zero forwards driving torque to the wheel, and the controlunit provides a braking command to apply a braking torque to the wheelto slow rotation of the wheel while the aircraft taxi speed is abovezero.

Preferably, the control unit (only) provides the braking command whenthe aircraft taxi speed is below a lowness threshold, such as 1-3, morepreferably 2 knots. For example, above this speed, the aircraft may onlydecelerate naturally, or due to manual brakes being applied.

The braking command may continue to be provided (and applied) even afterthe aircraft taxi speed has reduced to zero. For example, frictionbrakes may still be commanded to be applied.

The control panel may be for location in a cockpit of the aircraft.

Such a system allows a pilot, or other user, to control the aircraftspeed from a forwards speed to zero speed. This is done in a controlledmanner, avoiding any jerkiness or sudden braking. Without the activecontrol (by the control system) of the reduction in aircraft speed, thepilot themselves would have to use the aircraft brakes (through thebrake pedals) to control the stopping of the aircraft. This could leadto jerkiness and sudden braking and could be uncomfortable forpassengers. In addition, such a system effectively provides anadditional parking brake functionality.

The drive system may comprise a pinion gear, driveable by a motor, and adriven gear attached to the wheel, the pinion gear being engageable withthe driven gear to drive rotation of the driven gear, and wherein thetorque command to provide zero forwards driving torque to the wheelincludes a command to disengage the pinion gear and driven gear.

This ensures that no driving torque (or in fact any significant torque)is provided to or applied to the wheel by the drive system.

The command to disengage the pinion gear and driven gear may be givenwhen the indication of the aircraft taxi speed is above a predeterminedhighness threshold. This may be done to prevent jamming of the piniongear and driven gear. For example, this may be at a forward speed of 30knots or higher. 1 knot is approximately equal to 0.514 m/s.

This may be a useful way of providing zero driving torque at a highspeed, where there is significant energy involved and where leaving thedrive system engaged may cause significant regenerative braking andexcessive heat generation that may not easily be able to be dissipated,and damage.

Preferably, the drive system comprises a pinion gear driveable by amotor, the pinion gear being arrangeable to drive rotation of the wheel,and wherein the torque command to provide zero forwards driving torqueto the wheel includes a command to reduce the driving torque provided bythe motor to the pinion gear to zero.

More preferably, the command to reduce the driving torque provided bythe motor to the pinion gear to zero is given when the indication of theaircraft taxi speed is below a predetermined lowness threshold.

For example, this may be at a forward speed of 30 knots or lower.

This may be a useful way of providing zero driving torque at a lowspeed, where there is less energy involved and where leaving the drivesystem engaged does not cause significant regenerative braking andtherefore no excessive heat generation. There is also less risk ofjamming. Of course, regenerative braking will act to slow rotation ofthe wheel.

The highness threshold may be the same as the lowness threshold. Inother words, at that speed threshold the command changes.

Preferably, the braking command to apply a braking torque to the wheelto slow rotation of the wheel includes a command to a braking system ofthe aircraft to apply a braking torque to the wheel.

For example, the braking system may be a friction braking system.

The control system may also control brakes, for example friction brakes,of the wheel or aircraft. The brakes may be controlled directly from thecontrol system or may be controlled by the drive system. For example,the drive system may receive the braking command from the control unitand then provide a braking command to the brakes.

More preferably, the command to the braking system of the aircraft isgiven when the indication of the aircraft taxi speed is low.

For example, at a forward speed of 1 knot or lower.

This may be a useful way of providing a braking torque at a low speed,where the aircraft needs to be stopped.

Preferably, the braking command to apply a braking torque to the wheelto slow rotation of the wheel includes a command to the drive system ofthe aircraft to apply a braking torque to the wheel.

More preferably, the drive system is commanded to provide a regenerativebraking torque.

This may be provided by having the pinion gear and driven gear engagedwith each other, or the pinion gear, and therefore the motor, otherwiseengaged with the wheel. Here, the motor being connected to the wheel,and bring driven backwards by the wheel, causes a regenerative brakingeffect on the wheel.

Preferably, the command to the drive system of the aircraft is givenwhen the indication of the aircraft taxi speed is low.

For example, at a forward speed of 1-3 knots or lower, preferably at 2knots or lower.

This may be a useful way of providing a braking torque at a low speed,where there is less energy involved and where regenerative braking wouldnot cause excessive heat generation.

According to a second aspect of the invention there is also provided acontrol system for controlling a landing gear drive system on anaircraft, the drive system being capable of driving rotation of a wheelof the aircraft, the control system comprising a control panel, providedwith a controller, the controller having at least two forward motionsettings; a low forward speed setting, and a high forward speed setting,a control unit for receiving a control input from the controller, andfor providing a torque command to be applied to the wheel, and a speedsensor for sensing an aircraft taxi speed and for providing anindication of the aircraft taxi speed to the control unit, wherein thecontrol unit is arranged such that, when the controller is in the lowforward speed setting, the control unit provides a torque command to thedrive system, based on the indication of the aircraft taxi speed, tomaintain the aircraft taxi speed at or near a desired speed.

The control panel may be for location in a cockpit of the aircraft.

The aircraft speed may be maintained within a small range around adesired speed level, for example, the speed may be maintained with 0.1knots of a desired speed. Hence, if the aircraft speed is indicated asbeing higher than the desired speed, the torque command provided isreduced and if the aircraft speed is indicated as slower than thedesired speed, the torque command provided is increased. The desiredspeed may be 2 knots. This allows the speed of the aircraft to becontrolled, without active control by the pilot, or user. Hence, thetaxiing is likely to be much smoother, as there would be no need for thepilot to use the brake pedals, for example.

Alternatively, or additionally, regenerative braking may be used tomaintain the aircraft speed within the small range. For example, if theaircraft speed is indicated as being higher than the desired speed, theregenerative braking is increased, and if the aircraft speed isindicated as slower than the desired speed, the regenerative braking isdecreased.

The high forward speed setting may comprise a range of sub-settings, forexample, determined by the positioning of the controller within the highspeed setting.

Preferably, the desired speed is within the range between 1 and 3 knots,preferably 1.5 to 2.5 knots and more preferably 1.75 to 2.25 knots.

This is approximately walking speed and allows someone to walk alongwith the aircraft during taxiing.

Preferably, the control unit is arranged such that, when the controlleris in the high forward speed setting, the control unit provides a torquecommand to the drive system, based on a positioning of the controllerwithin the high speed setting.

For example, if the controller is positioned at a lower end of the highspeed setting, the torque command would be low. The torque command wouldstill be higher than that of the low speed setting. In other words, inthe high speed setting, the speed of the aircraft (for the same groundslope angle and/or conditions) is higher than the desired speed of thelow speed setting. For example, if the controller is positioned at ahigher end of the high speed setting, the torque command would be high.

In other words, in the high speed setting, the torque commanded is as afunction of an indication of relative power level desired. It is notrelated to a function of the aircraft speed.

Preferably, the controller has a zero speed setting, and wherein thecontrol unit is arranged such that, when the controller is moved from aforward motion setting to the zero speed setting the control unitprovides a torque command to the drive system to provide zero forwardsdriving torque to the wheel, and the control unit provides a brakingcommand to apply a braking torque to the wheel to slow rotation of thewheel while the aircraft taxi speed is above zero.

In other words, the control system of the second aspect may include thezero speed setting of the first aspect of the invention and any of thedependent features of this aspect.

According to a third aspect of the invention there is also provided acontrol system for controlling a landing gear drive system on anaircraft, the drive system being capable of driving rotation of a wheelof the aircraft, the control system comprising a control panel, providedwith a controller, the controller having at least two power settings; anormal power setting, and a boost power setting, and a control unit forreceiving a control input from the controller, and for providing atorque command to be applied to the wheel, wherein the control unit isarranged such that, when the controller is in the normal power setting,the control unit provides a torque command to the drive system toprovide a driving torque to the wheel up to a first power level, andwherein the control unit is arranged such that, when the controller isin the boost power setting, the control unit provides a torque commandto the drive system to provide a driving torque to the wheel at a secondpower level, higher than the first power level, and wherein thecontroller is biased away from the boost power setting and towards thenormal power setting.

The control panel may be for location in a cockpit of the aircraft.

Such a system allows a pilot, or other user, to be able to hold thecontroller in the boost power setting to provide an additional power(torque) level to the drive system. This may be useful for crossing arunway or for taxiing the aircraft uphill. The controller needs toactively be held in the boost setting, against the biasing.

The biasing may be provided by a spring, for example.

Preferably, the second power level is 10% to 25% higher, more preferablybetween 15% and 20% higher, than the first power level. For example, thefirst power level may go up to 55 kVA and the second power level may be65 kVA (18% higher).

Preferably, the control unit is arranged to reduce the torque command tothe first power level, if the controller is in the boost power settingand if an indication of the additional power provided to the drivesystem in the boost power setting has reached a set limit.

For example, this set limit could be a time period that the controllerhas been in the boost setting. For example, it may be 30 seconds or 1minute.

For example, this set limit may be an amount of additional power, overtime, has been provided in the boost power setting.

The control unit may also be arranged such that no additional power isprovided, even when in the boost setting, until a period of time haspassed since providing additional power. That time period may be 30seconds or 1 minute, for example.

The control unit may alternatively be arranged such that no additionalpower is provided, even when in the boost setting, until a reduction inpower provided, over time, has been provided in the normal powersetting. For example, this may be equivalent to the controller being ata maximum position within the normal power setting for 1 minute. It maybe equivalent to the controller being at a 90% position within thenormal power setting for 30 seconds.

Preferably, the additional power in the boost power setting is providedby the same power source that supplies the power of the normal powersetting.

This may be from an APU (Auxiliary Power Unit) or a battery, forexample.

Alternatively, the additional power in the boost power setting isprovided by a different power source that that which supplies the powerof the normal power setting.

For example, the power supplied in the normal power setting may besupplied from a battery and the additional power supplied in the boostpower setting may be supplied by the APU (or vice versa).

Preferably, both of the power settings are forward motion settings.

More preferably, the normal power setting has two sub-settings; a lowforward speed setting, and a high forward speed setting, wherein thecontrol system further comprises a speed sensor for sensing an aircrafttaxi speed and for providing an indication of the aircraft taxi speed tothe control unit, and wherein the control unit is arranged such that,when the controller is in the low forward speed setting, the controlunit provides a torque command to the drive system, based on theindication of the aircraft taxi speed, to maintain the aircraft taxispeed at or near a desired speed.

In other words, the control system of the third aspect may include thetwo forward speed settings of the second aspect of the invention and anyof the dependent features of this aspect.

Preferably, the controller has a zero speed setting, and wherein thecontrol unit is arranged such that, when the controller is moved from aforward motion setting to the zero speed setting the control unitprovides a torque command to the drive system to provide zero forwardsdriving torque to the wheel, and the control unit provides a brakingcommand to apply a braking torque to the wheel to slow rotation of thewheel while the aircraft taxi speed is above zero.

In other words, the control system of the third aspect may include thezero speed setting of the first aspect of the invention and any of thedependent features of this aspect.

According to a fourth aspect of the invention there is also provided acontrol system for controlling a landing gear drive system on anaircraft, the drive system being capable of driving rotation of a wheelof the aircraft, the control system comprising a control panel, providedwith a controller, the controller having a backwards motion setting, acontrol unit for receiving a control input from the controller, and forproviding a torque command to be applied to the wheel, and a speedsensor for sensing an aircraft taxi speed and for providing anindication of the aircraft taxi speed to the control unit, wherein thecontrol unit is arranged such that, when the controller is in thebackwards motion setting, the control unit provides a backwards drivingtorque command to the drive system, based on the indication of theaircraft taxi speed, to maintain the backwards aircraft taxi speed at ornear a desired speed.

The control panel may be for location in a cockpit of the aircraft.

The aircraft speed may be maintained within a small range around adesired speed level, for example, the speed may be maintained with 0.1knots of a desired speed. Hence, if the aircraft speed is indicated asbeing higher than the desired speed, the torque command provided isreduced and if the aircraft speed is indicated a slower than the desiredspeed, the torque command provided is increased. The desired speed maybe 2 knots.

This allows the backwards speed of the aircraft to be controlled,without active control by the pilot, or user. Hence, the taxiing islikely to be much smoother, as there would be no need for the pilot touse the brake pedals, for example.

Alternatively, or additionally, regenerative braking may be used tomaintain the aircraft speed within the small range. For example, if theaircraft speed is indicated as being higher than the desired speed, theregenerative braking is increased, and if the aircraft speed isindicated as slower than the desired speed, the regenerative braking isdecreased.

Preferably, the desired speed is within the range between 1 and 3 knots,preferably 1.5 to 2.5 knots and more preferably 1.75 to 2.25 knots.

This is approximately walking speed and allows someone to walk alongwith the aircraft during taxiing.

Preferably, the controller has a zero speed setting, and wherein thecontrol unit is arranged such that, when the controller is moved from aforward motion setting to the zero speed setting the control unitprovides a torque command to the drive system to provide zero forwardsdriving torque to the wheel, and the control unit provides a brakingcommand to apply a braking torque to the wheel to slow rotation of thewheel while the aircraft taxi speed is above zero.

In other words, the control system of the fourth aspect may include thezero speed setting of the first aspect of the invention and any of thedependent features of this aspect.

Preferably, the controller has at least two forward motion settings; alow forward speed setting, and a high forward speed setting, and whereinthe control unit is arranged such that, when the controller is in thelow forward speed setting, the control unit provides a torque command tothe drive system, based on the indication of the aircraft taxi speed, tomaintain the aircraft taxi speed at or near a desired speed.

In other words, the control system of the fourth aspect may include thetwo forward speed settings of the second aspect of the invention and anyof the dependent features of this aspect.

Preferably, the controller has at least two power settings; a normalpower setting, and a boost power setting, wherein the control unit isarranged such that, when the controller is in the normal power setting,the control unit provides a torque command to the drive system toprovide a driving torque to the wheel up to a first power level, andwherein the control unit is arranged such that, when the controller isin the boost power setting, the control unit provides a torque commandto the drive system to provide a driving torque to the wheel at a secondpower level, higher than the first power level, and wherein thecontroller is biased away from the boost power setting and towards thenormal power setting.

In other words, the control system of the fourth aspect may include theboost power setting of the third aspect of the invention and any of thedependent features of this aspect.

The normal power setting may include the two forward motion settings ofthe second aspect.

According to a fifth aspect of the invention there is also provided acontrol system for controlling a landing gear drive system on anaircraft, the drive system being capable of driving rotation of a wheelof the aircraft, the control system comprising a control panel, providedwith a controller, the controller having at least two settings; abackwards motion setting, and a zero speed setting, a control unit forreceiving a control input from the controller, and for providing atorque command to be applied to the wheel, and a speed sensor forsensing an aircraft taxi speed and for providing an indication of theaircraft taxi speed to the control unit, wherein the control unit isarranged such that, when the controller is moved from the backwardsmotion setting to the zero speed setting the control unit provides atorque command to the drive system to provide zero backwards drivingtorque to the wheel, and the control unit provides a braking command toapply a braking torque to the wheel to slow rotation of the wheel whilethe aircraft taxi speed is above zero.

The braking command may continue to be provided (and applied) even afterthe aircraft taxi speed has reduced to zero. For example, frictionbrakes may still be commanded to be applied. Such a system mayeffectively provide an additional parking brake functionality.

The control panel may be for location in a cockpit of the aircraft.

Preferably, the drive system comprises a pinion gear, driveable by amotor, the pinion gear being arrangeable to drive rotation of the wheel,and wherein the torque command to provide zero backwards driving torqueto the wheel includes a command to reduce the backwards driving torqueprovided by the motor to the pinion gear to zero.

Preferably, the braking command to apply a braking torque to the wheelto slow rotation of the wheel includes a command to a braking system ofthe aircraft to apply a braking torque to the wheel.

For example, the braking system may be a friction braking system.

The control system may also control brakes, for example friction brakes,of the wheel or aircraft. The brakes may be controlled directly from thecontrol system or may be controlled by the drive system. For example,the drive system may receive the braking command from the control unitand then provide a braking command to the brakes.

Preferably, the braking command to apply a braking torque to the wheelto slow rotation of the wheel includes a command to the drive system ofthe aircraft to apply a braking torque to the wheel.

More preferably, the braking command includes a command to the drivesystem to provide a regenerative braking torque.

This may be provided by having the pinion gear and driven gear engagedwith each other, or the pinion gear, and therefore the motor, otherwiseengaged with the wheel. Here, the motor being connected to the wheel,and being driven backwards by the wheel, causes a regenerative brakingeffect on the wheel.

Preferably, the controller has a zero speed setting, and wherein thecontrol unit is arranged such that, when the controller is moved from aforward motion setting to the zero speed setting the control unitprovides a torque command to the drive system to provide zero forwardsdriving torque to the wheel, and the control unit provides a brakingcommand to apply a braking torque to the wheel to slow rotation of thewheel while the aircraft taxi speed is above zero.

In other words, the control system of the fifth aspect may include thezero speed setting of the first aspect of the invention and any of thedependent features of this aspect.

Preferably, the controller has at least two forward motion settings alow forward speed setting, and a high forward speed setting, and whereinthe control unit is arranged such that, when the controller is in thelow forward speed setting, the control unit provides a torque command tothe drive system, based on the indication of the aircraft taxi speed, tomaintain the aircraft taxi speed at or near a desired speed.

In other words, the control system of the fifth aspect may include thetwo forward speed settings of the second aspect of the invention and anyof the dependent features of this aspect.

Preferably, the controller has at least two power settings a normalpower setting, and a boost power setting, wherein the control unit isarranged such that, when the controller is in the normal power setting,the control unit provides a torque command to the drive system toprovide a driving torque to the wheel up to a first power level, andwherein the control unit is arranged such that, when the controller isin the boost power setting, the control unit provides a torque commandto the drive system to provide a driving torque to the wheel at a secondpower level, higher than the first power level, and wherein thecontroller is biased away from the boost power setting and towards thenormal power setting.

In other words, the control system of the fifth aspect may include theboost power setting of the third aspect of the invention and any of thedependent features of this aspect.

The normal power setting may include the two forward motion settings ofthe second aspect.

Preferably, the controller has a backwards motion setting, and whereinthe control unit is arranged such that, when the controller is in thebackwards motion setting, the control unit provides a backwards drivingtorque command to the drive system, based on the indication of theaircraft taxi speed, to maintain the backwards aircraft taxi speed at ornear a desired speed.

In other words, the control system of the fifth aspect may include thebackwards motion setting of the fourth aspect of the invention and anyof the dependent features of this aspect.

According to a sixth aspect of the invention there is also provided anaircraft comprising an aircraft landing gear, having at least one wheelprovided with a drive system for driving rotation of the wheel, thedrive system comprising a motor, wherein the aircraft also comprises thecontrol system as described above, or control panel as described below,the control system or control panel being arranged to control the drivesystem.

According to a seventh aspect of the invention there is also provided amethod of controlling an aircraft landing gear drive system capable ofdriving rotation of a wheel of an aircraft, the method comprising thestep of using a control system or aircraft as described above or controlpanel as described below.

According to an eighth aspect of the invention there is also provided amethod of controlling an aircraft landing gear drive system capable ofdriving rotation of a wheel of an aircraft, the method comprising thesteps of moving a controller of a control panel from a forward motionsetting to a zero speed setting, and providing such a control input fromthe controller to a control unit, and, when the controller is in thezero speed setting, the control unit providing a torque command to thedrive system to provide zero forwards driving torque to the wheel, andthe control unit providing a braking command to apply a braking torqueto the wheel to slow rotation of the wheel while the aircraft taxi speedis above zero.

According to a ninth aspect of the invention there is also provided amethod of controlling an aircraft landing gear drive system capable ofdriving rotation of a wheel of an aircraft, the method comprising thesteps of positioning a controller of a control panel in a low forwardspeed setting and providing such a control input from the controller toa control unit, when the controller is in the low forward speed setting,the control unit providing a torque command to the drive system, basedon an indication of an aircraft taxi speed such that the aircraft taxispeed is maintained at or near a desired speed, and positioning thecontroller of the control panel in a high forward speed setting andproviding such a control input from the controller to a control unit.

According to a tenth aspect of the invention there is also provided amethod of controlling an aircraft landing gear drive system capable ofdriving rotation of a wheel of an aircraft, the method comprising thesteps of positioning a controller of a control panel in a normal powersetting and providing such a control input from the controller to acontrol unit, when the controller is in the normal power setting, thecontrol unit providing a torque command to the drive system to provide adriving torque to the wheel up to a first power level, positioning acontroller of a control panel in a boost power setting by urging thecontroller against a biasing force that biases the controller away fromthe boost power setting and towards the normal power setting, andproviding such a control input from the controller to a control unit,and when the controller is in the boost power setting, the control unitproviding a torque command to the drive system to provide a drivingtorque to the wheel at a second power level, higher than the first powerlevel.

According to an eleventh aspect of the invention there is also provideda method of controlling an aircraft landing gear drive system capable ofdriving rotation of a wheel of an aircraft, the method comprising thesteps of positioning a controller of a control panel in a backwardsmotion setting, and providing such a control input from the controllerto a control unit, and when the controller is in the backwards motionsetting, the control unit providing a backwards driving torque commandto the drive system, based on an indication of an aircraft taxi speedsuch that the backwards aircraft taxi speed is maintained at or near adesired speed.

According to a twelfth aspect of the invention there is also provided amethod of controlling an aircraft landing gear drive system capable ofdriving rotation of a wheel of an aircraft, the method comprising thesteps of moving a controller of a control panel from a backwards motionsetting to a zero speed setting, and providing such a control input fromthe controller to a control unit, and, when the controller is in thezero speed setting, the control unit providing a torque command to thedrive system to provide zero backwards driving torque to the wheel, andthe control unit providing a braking command to apply a braking torqueto the wheel to slow rotation of the wheel while the aircraft taxi speedis above zero.

According to a thirteenth aspect of the invention there is provided acontrol panel of an aircraft, the control panel provided with acontroller in the form of a rotary dial and having a forward motionsetting for controlling forwards driving rotation of a wheel of theaircraft, wherein the forward motion setting is located at leastpartially between 9 o'clock and 12 o'clock on the rotary dial.

The “o'clock” positions are defined in relation to normal hour positionsof a clock in a normal orientation, as viewed by a pilot. In otherwords, the 9 o'clock position is located at 270 degrees clockwise from a0 degrees bearing (12 o'clock).

This allows for forwards facing positions of the rotary dial (i.e.between 9 o'clock and 3 o'clock) to relate to commanded forwardsmovement of the aircraft. In addition, for most scenarios, commanding ahigher forwards speed involves moving the dial further forwards. Thismakes the controller more intuitive and easier to use.

Preferably, the forward motion setting is located substantially between9 o'clock and 12 o'clock on the rotary dial. In other words, if theforward motion setting is a region of the rotary dial, most of theforwards motion setting region is located between 9 o'clock and 12o'clock on the rotary dial.

Preferably, the forwards motion setting comprises a low forward speedsetting, for maintaining aircraft taxi speed at or near a desired lowspeed, and a high forward speed setting, wherein the high forward speedsetting is located substantially between 9 o'clock and 12 o'clock on therotary dial.

More preferably, the low forward speed setting is located(substantially) at 9 o'clock on the rotary dial.

Preferably, the controller has a zero speed setting, for commanding zerodriving torque to the wheel of the aircraft, wherein the zero speedsetting is located anti-clockwise from 9 o'clock on the rotary dial.

The zero speed setting may be between 6 o'clock and 9 o'clock on therotary dial. Hence, this is within an expected rotation range of a pilothand, so that a pilot is able to move to/from the zero speed settingwithout having to lift their hand off the controller.

More preferably, the zero speed setting is located between 8 o'clock and9 o'clock on the rotary dial.

Preferably, the controller has a backwards motion setting, forcontrolling backwards driving rotation of a wheel of the aircraft,wherein the backwards motion setting is located anti-clockwise from 9o'clock on the rotary dial.

The backwards motion setting may be between 6 o'clock and 9 o'clock onthe rotary dial. Hence, this is within an expected rotation range of apilot hand, so that a pilot is able to move to/from the backwards motionsetting without having to lift their hand off the controller.

More preferably, the backwards motion setting is located between 7o'clock and 8 o'clock on the rotary dial.

Preferably, the forwards motion setting comprises a normal powersetting, for providing a torque command up to a first power level, and aboost power setting, for providing a torque command at a second powerlevel, higher than the first power level, wherein the normal powersetting is located substantially between 9 o'clock and 12 o'clock on therotary dial.

The normal power setting may encompass the low and/or the high forwardsspeed settings.

More preferably, the controller is biased away from the boost powersetting and towards the normal power setting.

Preferably, a maximum normal power setting is located substantially at12 o'clock on the rotary dial.

Preferably, the boost power setting is located clockwise from 12 o'clockon the rotary dial.

The boost power setting may be between 12 o'clock and 3 o'clock on therotary dial. Hence, this is within an expected rotation range of a pilothand, so that a pilot is able to move to/from the boost power settingwithout having to lift their hand off the controller.

More preferably, the boost power setting is located between 12 o'clockand 1 o'clock on the rotary dial.

The control panel of the thirteenth aspect may be part of a controlsystem of any of the other aspects of the invention.

It will of course be appreciated that features described in relation toone aspect of the present invention may be incorporated into otheraspects of the present invention. For example, the method of theinvention may incorporate any of the features described with referenceto the apparatus of the invention and vice versa.

DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofexample only with reference to the accompanying schematic drawings ofwhich:

FIG. 1 shows a front schematic view of an example controller;

FIG. 2a shows a front schematic view of a controller according to afirst embodiment of the invention;

FIG. 2b shows a front schematic view of the controller of FIG. 2a , alsoshowing a dial switch;

FIG. 3 shows a schematic diagram of a control system including thecontroller of FIGS. 2a and 2 b;

FIG. 4 shows a schematic diagram of a controller according to a secondembodiment of the invention; and

FIG. 5 shows a front view of an aircraft including the control system ofFIG. 3.

DETAILED DESCRIPTION

FIG. 1 shows a front schematic view of an example controller 10, asdescribed above.

FIG. 2a shows a front schematic view of a controller 20 according to afirst embodiment of the invention.

In a similar way to the controller 10 of FIG. 1, the controller 20 has abackwards speed setting 21 and a (normal power) forward speed settingregion 23. When in the forward speed setting region 23, the systemprovides an amount of torque to the drive system based on the positionof a controller within the forward speed setting region 23. In otherwords, the controller 20 dictates how much torque is provided.

Also similar to FIG. 1, in the backwards speed setting 21, the amount ofbackwards driving torque supplied (and regenerative braking) is based onthe speed of the aircraft, such that the speed is maintained to be at ornear 2 knots (backwards). This enables the aircraft to be taxied at aspeed similar to walking speed, without a pilot, for example, having toactively manage the backwards speed.

When the controller is moved from the backwards speed setting to a zerospeed setting 27, the torque supplied is adjusted, and brakes applied,so as to slow the aircraft down to zero speed.

The controller has a maximum normal power setting 24. This is themaximum setting at which torque at that level can be continuouslysupplied. This is 55 kVA.

However, the controller 20 can be placed in a (forwards) boost powersetting 30. In this setting, an additional torque level is available, of18% more (65 kVA as opposed to 55 kVA). A spring (shown by arrow 31)biases the controller back to the maximum normal power setting 24.

The additional torque level is only available for a limited time, inthis embodiment, for 1 minute. After that, the torque level provided isat the same level as for the maximum normal power setting 24, even ifthe controller is held, for example by the pilot, against the spring 31,in the boost power setting 30.

The additional power in the boost power setting is provided by the samepower source that supplies the power of the normal power setting. Thisis from an APU (Auxiliary Power Unit) (not shown).

The additional torque can be used, temporarily, for example if theaircraft is going uphill or crossing a runway. This enables the aircraftto be effectively driven at a suitable speed, but does not generallyoverburden a power source of the landing gear drive system, or affectthe health of the power source equipment.

There is also a (normal power) low forwards speed setting 28. In thissetting, the amount of forwards driving torque supplied (by a landinggear drive system), and the amount of regenerative braking, is based onthe speed of the aircraft (sensed by a sensor), such that the speed ismaintained to be at or near 2 knots (forwards). This enables theaircraft to be taxied at a speed similar to walking speed, without apilot, for example, having to actively manage the forwards speed. Thismakes parking the aircraft (nose in) at an aircraft gate much easier andwill likely prevent damage/risk from a low speed impact occurringbetween an aircraft and an aircraft gate.

When the controller 20 is moved from the low forwards speed setting 28to the zero speed setting 27, the driving torque supplied is adjusted(for example by reducing the forwards driving torque to zero, byreducing the torque supplied to the drive system or by disengaging thedrive system from an aircraft wheel), and brakes may be applied, so asto slow the aircraft down to zero speed.

Hence, when the controller 20 is moved from the backwards speed setting21 or low forwards speed setting 28 to the zero speed setting 27, theaircraft is actively slowed to have zero speed. Hence, the zero speedsetting 27 always acts as a supplement to a park brake system of theaircraft.

FIG. 2b shows a front schematic view of the controller 200 of FIG. 2a ,also showing a dial switch 32.

It is this dial switch 32 that is rotated into and out of the differentsettings 21, 27, 28, 23, 24, 30.

FIG. 3 shows a schematic diagram of a control system 200 including thecontroller 20 of FIGS. 2a and 2 b.

The controller 20 is part of a control panel 40. The control panel 40has a control signal line 41 to a control unit 60. This is how thesetting of the controller 20 is sent to the control unit 60.

There is also an aircraft speed sensor 50 that has a speed indicationsignal line 51 to the control unit 60. This is how the control unit hasan indication of the aircraft taxi speed, during use.

The control unit 60 includes a computer to calculate and provide twooutputs; an output command for the landing gear drive system and anoutput command for the friction brake system.

The output command for the drive system is provided to the drive system(represented by box 72) by the drive system command line 71. This may bea disengagement command, a re-engagement command, a regenerating brakingtorque command (i.e. a command for the drive system to remain engagedwith no driving torque provided), a forwards driving torque command or abackwards driving torque command.

The output command for the friction brake system is provided to thebrake system (represented by box 82) by the brake system command line81. This is a braking torque command.

The drive system 72 (not shown in detail) comprises a drive systemsimilar to as shown in GB 2528966 A. It has a drive pinion driven by atorque controlled motor and a driven gear attached to a wheel of theaircraft. The drive pinion can be selectively moved in and out ofmeshing engagement with the driven gear. It is this engagement that iscontrolled by the disengagement and re-engagement commands, for example.

The control unit 60 is provided with two sets of input values.

Firstly, a speed threshold set of values (Vt) represented by box 61. Inthis example, this is just one speed value. Above this threshold taxispeed value (here, 30 knots), the control unit will command the drivesystem to disengage the pinion gear and driven gear (disengagementcommand), as will be described below. Below this threshold taxi speedvalue, the control unit will command the drive system to remain engaged,as will be described below.

Secondly, a set of target speed values, represented by box 62. Here,these are a low forwards speed setting of 2 knots and a backwards speedsetting of 2 knots. In other words, these are the desired aircraft taxispeeds in settings 28 and 21 respectively.

FIG. 5 shows a front view of an aircraft 2000 including the controlsystem 200 of FIG. 3.

The aircraft 2000 is provided with a nose landing gear 2100 with twowheels 2101, 2102. The aircraft also has a right hand (viewed from theforwards direction of the aircraft) landing gear 2200 with two wheels2201, 2202. The aircraft also has a left hand landing gear 2300 with twowheels 2301, 2302.

The aircraft 2000 is also provided with the control system 200 describedabove (not shown in FIG. 5), a drive system 72 (not shown in FIG. 5) fordriving one or more main landing gear wheels 2201, 2202, 2301, 2302 anda braking system 82 (not shown in FIG. 5).

In use, a pilot uses the controller 20 to adjust the taxi speed of theaircraft 2000, through use of the drive system 72 and brake system 82.The required commands of the drive system 72 and brake system 82 aredecided by the control unit 60, based on the controller 20 setting (fromsignal line 41) and the aircraft taxi speed (from line 51).

For example, when the controller 20 is in the backwards speed setting21, the control unit 60 commands the drive system 72 provide a backwardsdriving torque, and regenerative braking, to achieve the target speed(here, 2 knots backwards) provided in box 62. This is done as a feedbackloop, based on the taxi speed detected by the aircraft speed sensor 50.

When the controller 20 is moved to the zero speed setting 27, thecontrol unit 60 commands the drive system to stop providing a backwardsdriving torque. In addition, the control unit 60 will command thefriction brake system 82 to apply the friction brakes to apply a brakingtorque to reduce the backwards speed of the aircraft to zero.

When the controller 20 is moved to the low forwards speed setting 28,the control unit 60 will command the drive system 72 to apply a forwardsdriving torque, and provide regenerative braking. This will be done toachieve the target speed (here, 2 knots forwards) provided in box 62.This is done as a feedback loop, based on the taxi speed detected by theaircraft speed sensor 50.

When the controller 20 is then moved into the high forwards speed region23, the torque commanded from the drive system 72 is not related orconstrained by the aircraft speed. Instead, the drive system 72 iscommanded to provide a torque level corresponding to the relativeposition of the controller dial 32 within the region 23. For example, ifthe dial 32 is only just above the low speed setting 28, the torquedemanded will be low (but generally enough to provide an aircraft speedof more than 2 knots). If the dial 32 is just below the maximum normalpower setting 24, the torque demanded will be high (almost at themaximum normal torque available).

If the pilot wishes to increase the torque demanded further, they mayactively apply pressure to the dial switch 32 against the spring 31 tohold the dial switch in the boost power setting 30. If the pilotreleases the dial switch 32 it will be urged back (by the spring 31) tothe maximum normal power setting 24. The boost power setting 30 is ableto provide 18% more power than in the maximum normal power setting 24.

When the dial switch 32 is in the boost power setting 30, the torquedemanded corresponds to the boost power setting (65 kVA).

However, if the dial switch 32 has been in the boost power setting for 1minute (60 seconds), the torque demanded from the drive system 72 willbe reduced to that of the maximum normal power level 24 by the controlunit 60. This can then be re-increased after 1 minute (60 seconds) haspassed.

When the controller 20 is moved from a relatively higher speed settingto a relatively lower speed setting in region 23, the control unitcommands that the drive system 72 provides an appropriate lower torque,based on the position of the dial within the region 23. No frictionbraking command is given and so the aircraft slows naturally, or withmanual braking by the pilot.

When the controller 20 is moved to the low speed setting 28, from asetting in the high forwards speed setting region 23 (or boost powersetting 30), the control unit 60 commands the drive system 72 and thebrake system 82 such that the aircraft reduces speed to, and thenmaintains the target speed, of 2 knots.

Initially, if the aircraft speed is below 3 knots, for example, thebrake system 82 will be commanded to provide a braking torque to reducethe aircraft speed.

Once the aircraft speed has reduced to 2 knots, the drive system 72provides a driving torque and a regenerative braking torque to maintainthe aircraft speed at 2 knots.

If the initial aircraft speed is above 3 knots, for example, the pilotmay have to actively use the brake pedals to reduce the aircraft speedto 3 knots. After this, the brake system 82 will be commanded to providea braking torque to reduce the aircraft speed further.

When the controller 20 is moved to the zero speed setting 27 from thelow forwards speed setting 28, the control unit 60 commands such thatthe aircraft speed reduces to zero.

The brake system 82 is commanded to provide a friction braking torque todo so.

FIG. 4 shows a schematic diagram of a controller 20′, on a control panel40′, according to a second embodiment of the invention. The controller20′, and its use, is similar to that described for controller 20.However, the differences, in relation to the setting positions, will bedescribed.

Here, the dial switch 32′ has the different settings arranged atdifferent angles about the dial. The maximum normal power setting 24′ islocated at “12 o'clock” on the dial. The boost power setting 30′ islocated 25 degrees further round (clockwise). The low forward speedsetting 28′ is located at 90 degrees anti-clockwise (i.e. at “9o'clock”) from the maximum normal power setting 24′. The zero speedsetting 27′ is located 20 degrees further anti-clockwise (i.e. 110degrees anti-clockwise from the maximum normal power setting 24′).Finally, the backward speed setting 21′ is located 25 degrees furtheranti-clockwise (i.e. 135 degrees anti-clockwise from the maximum normalpower setting 24′).

These setting positions provide that substantially all of the forwardsettings are in a forward facing position (i.e. between “9 o'clock” and“3 o'clock” on the dial) and that, for most scenarios, moving to agreater forward speed (e.g. within the region 23′) involves movement ofthe dial to a more forward position (i.e. moving from 9 o'clock” to 12o'clock”).

Whilst the present invention has been described and illustrated withreference to particular embodiments, it will be appreciated by those ofordinary skill in the art that the invention lends itself to manydifferent variations not specifically illustrated herein. By way ofexample only, certain possible variations will now be described.

The reduction of torque level to that of the maximum normal powersetting 24 may occur after a different length of time, for example 30seconds or 90 seconds. The reduction may instead occur when a certainamount of additional torque has been employed.

The re-increase of torque level to that of the boost power setting 30may occur after a different length of time, for example 30 seconds or 90seconds. The re-increase may instead occur when a certain amount ofreduction is torque has been achieved. For example, it may be equivalentto when the torque provided has been at a mid-power level (half way inregion 23) for 30 seconds or at the maximum power level 24 for 1 minute.

The re-increase and/or cutting off of boost power level may be based onthe overall power consumption/demand of the drive system over a periodof time, for example, the previous 2 or 3 minutes.

The additional torque level associated with the boost power setting 30may instead be provided by a different power source from that whichsupplies the power of the normal power setting. For example, this may beby a battery, if the normal torque is provided by an APU.

The normal torque level may be provided by one or more power sources,other than an APU, for example a battery. Here, if the additional torquelevel is provided by a different power source, it may be from an APU.

When the controller 20 is moved so as to reduce the aircraft speed (i.e.from a forwards speed setting to a lower speed setting or the zero speedsetting 27), a regenerative braking torque may be provided by thelanding gear drive system so as to slow the aircraft down to zero speed,or a braking torque from a brake system of the aircraft may be provided,or both.

Different braking methods may be employed at different aircraft speeds.

For example, at a low speed (e.g. under 2 knots) friction braking andregenerative braking may be commanded.

The speed threshold(s) may be any suitable, appropriate speed, chosen toprevent appropriate damage to the drive system. They may be variable,provided to the control unit 60 by a further input.

The target speed values (low forwards speed setting and backwards speedsetting) may be any suitable, appropriate speed, for example 1 knot, 1.5knots, 2.5 knots, 3 knots etc. They may be variable, provided to thecontrol unit 60 by a further input.

The brake system of the aircraft may also or instead of friction brakes,include other braking means.

Any suitable drive system may be used.

The drive system may drive any number of wheels of the aircraft,including one or more of nose or main landing gear wheels.

Any suitable controller may be used. If a dial switch 32 like describedhere is used, any suitable angles may be used for the differentsettings.

The control system 200 may not include the brake system and instead, thepilot may command the brake system directly from brake pedals, or othercontrols, in the cockpit, for example.

As a further alternative, the command to the brake system 82 may comevia the drive system 72 (i.e. not directly from the control unit 60).

Where in the foregoing description, integers or elements are mentionedwhich have known, obvious or foreseeable equivalents, then suchequivalents are herein incorporated as if individually set forth.Reference should be made to the claims for determining the true scope ofthe present invention, which should be construed so as to encompass anysuch equivalents. It will also be appreciated by the reader thatintegers or features of the invention that are described as preferable,advantageous, convenient or the like are optional and do not limit thescope of the independent claims. Moreover, it is to be understood thatsuch optional integers or features, whilst of possible benefit in someembodiments of the invention, may not be desirable, and may therefore beabsent, in other embodiments.

It should be noted that throughout this specification, “or” should beinterpreted as “and/or”.

1. A control system for controlling a landing gear drive system on anaircraft, the drive system being capable of driving rotation of a wheelof the aircraft, the control system comprising: a control panel,provided with a controller, the controller having at least two settings:i) a forward motion setting, and ii) a zero speed setting, a controlunit for receiving a control input from the controller, and forproviding a torque command to be applied to the wheel, and a speedsensor for sensing an aircraft taxi speed and for providing anindication of the aircraft taxi speed to the control unit, wherein thecontrol unit is arranged such that, when the controller is moved fromthe forward motion setting to the zero speed setting: a) the controlunit provides a torque command to the drive system to provide zeroforwards driving torque to the wheel, and b) the control unit provides abraking command to apply a braking torque to the wheel to slow rotationof the wheel while the aircraft taxi speed is above zero.
 2. A controlsystem as claimed in claim 1, wherein the drive system comprises apinion gear driveable by a motor, the pinion gear being arrangeable todrive rotation of the wheel, and wherein the torque command to providezero forwards driving torque to the wheel includes a command to reducethe driving torque provided by the motor to the pinion gear to zero. 3.A control system as claimed in claim 2, wherein the command to reducethe driving torque provided by the motor to the pinion gear to zero isgiven when the indication of the aircraft taxi speed is below apredetermined lowness threshold.
 4. A control system as claimed in claim1, wherein the braking command to apply a braking torque to the wheel toslow rotation of the wheel includes a command to a braking system of theaircraft to apply a braking torque to the wheel.
 5. A control system asclaimed in claim 4, wherein the command to the braking system of theaircraft is given when the indication of the aircraft taxi speed is low.6. A control system as claimed in claim 1, wherein the braking commandto apply a braking torque to the wheel to slow rotation of the wheelincludes a command to the drive system of the aircraft to apply abraking torque to the wheel, wherein the drive system is commanded toprovide a regenerative braking torque.
 7. A control system as claimed inclaim 6, wherein the command to the drive system of the aircraft isgiven when the indication of the aircraft taxi speed is low.
 8. Acontrol system for controlling a landing gear drive system on anaircraft, the drive system being capable of driving rotation of a wheelof the aircraft, the control system comprising: a control panel,provided with a controller, the controller having at least two forwardmotion settings: i) a low forward speed setting, and ii) a high forwardspeed setting, a control unit for receiving a control input from thecontroller, and for providing a torque command to be applied to thewheel, and a speed sensor for sensing an aircraft taxi speed and forproviding an indication of the aircraft taxi speed to the control unit,wherein the control unit is arranged such that, when the controller isin the low forward speed setting, the control unit provides a torquecommand to the drive system, based on the indication of the aircrafttaxi speed, to maintain the aircraft taxi speed at or near a desiredspeed.
 9. A control system as claimed in claim 8, wherein the desiredspeed is within the range between 1 and 3 knots, preferably 1.5 to 2.5knots and more preferably 1.75 to 2.25 knots.
 10. A control system forcontrolling a landing gear drive system on an aircraft, the drive systembeing capable of driving rotation of a wheel of the aircraft, thecontrol system comprising: a control panel, provided with a controller,the controller having at least two power settings: i) a normal powersetting, and ii) a boost power setting, and a control unit for receivinga control input from the controller, and for providing a torque commandto be applied to the wheel, wherein the control unit is arranged suchthat, when the controller is in the normal power setting, the controlunit provides a torque command to the drive system to provide a drivingtorque to the wheel up to a first power level, and wherein the controlunit is arranged such that, when the controller is in the boost powersetting, the control unit provides a torque command to the drive systemto provide a driving torque to the wheel at a second power level, higherthan the first power level, and wherein the controller is biased awayfrom the boost power setting and towards the normal power setting.
 11. Acontrol system as claimed in claim 10, wherein the control unit isarranged to reduce the torque command to the first power level, if thecontroller is in the boost power setting and if an indication of theadditional power provided to the drive system in the boost power settinghas reached a set limit.
 12. A control system for controlling a landinggear drive system on an aircraft, the drive system being capable ofdriving rotation of a wheel of the aircraft, the control systemcomprising: a control panel, provided with a controller, the controllerhaving a backwards motion setting, a control unit for receiving acontrol input from the controller, and for providing a torque command tobe applied to the wheel, and a speed sensor for sensing an aircraft taxispeed and for providing an indication of the aircraft taxi speed to thecontrol unit, wherein the control unit is arranged such that, when thecontroller is in the backwards motion setting, the control unit providesa backwards driving torque command to the drive system, based on theindication of the aircraft taxi speed, to maintain the backwardsaircraft taxi speed at or near a desired speed.
 13. A control system asclaimed in claim 12, wherein the desired speed is within the rangebetween 1 and 3 knots, preferably 1.5 to 2.5 knots and more preferably1.75 to 2.25 knots.
 14. A control system for controlling a landing geardrive system on an aircraft, the drive system being capable of drivingrotation of a wheel of the aircraft, the control system comprising: acontrol panel, provided with a controller, the controller having atleast two settings: i) a backwards motion setting, and ii) a zero speedsetting, a control unit for receiving a control input from thecontroller, and for providing a torque command to be applied to thewheel, and a speed sensor for sensing an aircraft taxi speed and forproviding an indication of the aircraft taxi speed to the control unit,wherein the control unit is arranged such that, when the controller ismoved from the backwards motion setting to the zero speed setting: a)the control unit provides a torque command to the drive system toprovide zero backwards driving torque to the wheel, and b) the controlunit provides a braking command to apply a braking torque to the wheelto slow rotation of the wheel while the aircraft taxi speed is abovezero.
 15. A control system as claimed in claim 14, wherein the drivesystem comprises a pinion gear driveable by a motor, the pinion gearbeing arrangeable to drive rotation of the wheel, and wherein the torquecommand to provide zero backwards driving torque to the wheel includes acommand to reduce the backwards driving torque provided by the motor tothe pinion gear to zero.
 16. A control system as claimed in claim 14,wherein the braking command to apply a braking torque to the wheel toslow rotation of the wheel includes a command to a braking system of theaircraft to apply a braking torque to the wheel.
 17. A control system asclaimed in claim 14, wherein the braking command to apply a brakingtorque to the wheel to slow rotation of the wheel includes a command tothe drive system of the aircraft to apply a braking torque to the wheel,wherein the drive system is commanded to provide a regenerative brakingtorque.
 18. An aircraft comprising an aircraft landing gear, having atleast one wheel provided with a drive system for driving rotation of thewheel, the drive system comprising a motor, wherein the aircraft alsocomprises the control system of claim 1, the control system or controlpanel being arranged to control the drive system.
 19. A method ofcontrolling an aircraft landing gear drive system capable of drivingrotation of a wheel of an aircraft, the method comprising the step ofusing a control system of claim
 1. 20. A control panel of an aircraft,the control panel provided with a controller in the form of a rotarydial and having a forward motion setting for controlling forwardsdriving rotation of a wheel of the aircraft, wherein the forward motionsetting is located at least partially between 9 o'clock and 12 o'clockon the rotary dial.